The present invention relates to a stopper apparatus, provided in a rotation axis section wherein a relative rotation is carried out between two members around one rotation axis, for restricting the rotation angle of one member with respect to the other member. The present invention also relates to a robot equipped with the above-mentioned stopper apparatus.
At a rotation axis section wherein a relative rotation is carried out between two members around one rotation axis, for example, at the connection section between the base section and the rotary drum, at the connection section between the rotary drum and the arm section and at the connection section between an arm section and another arm section of an industrial robot, the relative rotation between the two members is required to be restricted in a constant range. This is because if the relative rotation is allowed infinitely, the wiring or piping extended between the above-mentioned two members are twisted excessively and damaged. This kind of restriction is usually accomplished by using hardware or software of a controller. However, a mechanical stopper is required to prevent machine damage from overspeed owing to trouble, such as runaway of a controller. Furthermore, a relative rotation of 360° or more is required occasionally in uses of the above-mentioned industrial robot. Hence, a mechanical stopper for restricting the relative rotation between the above-mentioned two members in a range exceeding 360° is necessary.
Patent Document 1 or Patent Document 2 discloses a mechanical stopper comprising a first engagement piece secured to a rotary member and a second engagement piece installed on a stationary member so as to be freely slidable in a constant range, wherein when the above-mentioned first engagement piece makes contact with the above-mentioned second engagement piece, the above-mentioned first and second engagement pieces are integrated and move in a constant range and then stop, whereby a relative rotation range exceeding 360° is offered.
[Patent Document 1]
Unexamined Japanese Patent Application Publication No. Hei07-136972
[Patent Document 2]
Unexamined Japanese Patent Application Publication No. Hei10-225890
However, the above-mentioned mechanical stopper has the following problems. Since it has a sliding section, there is a danger of generating abrasion powder, whereby the mechanical stopper is not suited for robots requiring cleanness, such as robots for use in semiconductor production. In addition, even in a case where grease or the like is used at the sliding section to avoid abrasion, if gas evaporating from grease or the like pollutes clean environments, problems will occur. Furthermore, the number of components is large, and a great amount of time and effort is required for assembly, thereby causing a problem in raising production costs.